using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace demo2
{
    class Square:shape
    {
        public double sideLen;

        public void GetArea()
        {
            Console.WriteLine("请输入正方形边长：");
            string str1 = Console.ReadLine();
            double a = double.Parse(str1);
            Console.WriteLine("正方形的面积为：" + (a*a));
        }
    }
}
